1. Field of the Invention
The present invention relates to a system for combining at least two signals having frequency bands different rom one another. One signal may be within the hundreds of Mhz range and a second signal may be within the tens of Gigahertz range. More particularly, the present invention relates to a system including numerous band-pass filters and ancillary circuits for each band to be combined, as well as a bridge or circuit connecting the filters. The invention also includes the combiner devices resulting from the system implementation.
2. Description of the Related Art
Combining two or more signals having different frequency bands on a sole carrier device, e.g., a cable, is a frequently encountered problem in the telecommunication's field. The combination must be made with the minimum possible space requirement by a device including, in addition to channel filters, auxiliary circuits that survey the characteristics of the signals to be combined, and signal the status of filters to control circuits, e.g., by motors. Tuning of filters must be made automatically.
The simplified scheme of FIG. 1A shows the frequency bands B1, B2, . . . Bn of the signals to be combined, and FIG. 1B represents blocks of circuits. F1, F2, . . . Fn are filters through which the frequency bands B1, B2, . . . Bn pass. C1, C2, . . . Cn indicate the ancillary circuits associated with each filter.
FIG. 2 represents the schematic front view of a combining circuit made up using the known techniques for combining two or more signals each having a band B1, B2, . . . Bn. Each filter F1, F2, . . . Fn is represented by a parallelepiped-shaped box (generally a resonant cavity) attached to box C1, C2, . . . Cn holding the ancillary circuits. A coupling line is provided at the output of each filter and is joined externally to two connectors Sa and Sb. The output Sb of each filter is joined to the input Sa of the following filter. The connector Sa of the first filter is closed on a reactive load (CR) that, without dissipating power, causes the signal coming from the input of each filter to be transmitted towards the input connector of the following filter.
The signals B1, B2, . . . Bn are assembled on the connector Sb of the first filter. These signals come from the input of all filters F1, F2,. . . Fn. CO' indicates the connection cable between C1 and F1 (FIG. 2b). This circuit has a series of drawbacks, such as excessive space requirements and difficulty of circuit connections among the filter couples.